Question

An object is placed 20 cm in front of a converging lens of focal length 30 cm. What is the position of the image?​

Answer 1

Answer:

Image is formed at a distance 12 cm from the lens to its right side.

Explanation:

Given,

An object is placed 20 cm in front of a converging lens of focal length 30 cm.

To find: the position of the image. (v)

Solution:

By sign convention,

Focal length (f) = + 30 cm

Distance of object (u) = -20 cm

From len's formula,

1 /f = 1/v - 1 / u

1 / 30 = 1 / v - 1 / (-20)

1 / 30 = 1 / v + 1 / 20

1 / v = 1 / 30 - 1/20

1 / v = (2+3) /60

1 / v = 5 / 60

or, v = 60 / 5 = +12 cm

Therefore, Image is formed at a distance 12 cm from the lens to its right side.